condense: Summarize data

In kleu046/wr.data.table: What the Package Does (One Line, Title Case)

Summarize data

Description

The condense function is similar to the summarize function in the dplyr package. It is simply a wrapper function using data.table syntax which performs a similar function as dplyr::summarize()

Variable names in characters need to be parsed into symbols first

Usage

condense(dt, ...)

Arguments

dt	input data.table
...	some parameters

Value

returns a data.table

Examples

## Not run: 
 dt <- data.table(data1)

 # using condense function in various ways
 dt|>condense(mean_mpg=mean(mpg))
 dt|>condense(mean_mpg=mean("mpg"))
 dt|>condense(mean_mpg=mean(mpg), sd_mpg=sd(mpg),count=.N)
 dt|>condense(mean_mpg=mean("mpg"), sd_mpg=sd(mpg),count=.N)

 # grouping data by columns
 dt|>set_group("vs","am")|>condense(mean_mpg=mean(mpg))
 dt|>set_group(vs,am)|>condense(mean_mpg=mean("mpg"), sd_mpg=sd(mpg),count=.N)
 dt|>set_group(vs)|>rn_cols(mpg=`miles per gallon`)|>condense(mean_mpg=mean(`miles per gallon`))

 # using a variable to represent the character name of a column
 myvar <- "mpg"
 dt|>
   set_group(vs)|>
   condense(mean_mpg=mean(eval(char_to_symbol(myvar))),
            sd_mpg=sd(eval(char_to_symbol(myvar))),
            max_mpg = max(eval(char_to_symbol(myvar))),
            min_mpg = min(eval(char_to_symbol(myvar))),
            count=.N)

## End(Not run)

kleu046/wr.data.table documentation built on April 25, 2022, 1:41 p.m.